The Po River has never fallen this low so early in the year, raising fears of a devastating drought in July in this corner of northern Italy.On the bank of one of its branches, farmer Federica Vidali looked anxiously at her sunflower field. The first bloom of the season has appeared, but part of the field is already dry and starting to crack.One of the two canals that irrigate it has been shut because the seawater would enter and damage the crops."We're left with the water that others are willing to leave us. But we're not second-division farmers!" Vidali told AFP.The Po River's flow has collapsed in a matter of days, dropping below 300 cubic meters per second, compared with an average of around 1,500 in June, according to Aipo, the interregional river agency."It has never dropped so fast, so early," said Stefano Calderoni of the Italian irrigation association (Anbi).Sandbanks are multiplying, depths fall to barely one meter in places, and the river's few remaining fishermen swelter in the heat."Before, we used to pass on the left; now the passage is to the right of the sandbank, and it's very, very narrow," said Daniela Cuoghi, a surveyor for Aipo.The many Alpine lakes that feed the Po Valley, Italy's agro-industrial heartland, are still about 60 percent full. But farmers are drawing heavily from the waterways to irrigate fields parched by the heat.